The removal of sulfur and nitrogen impurities from fossil fuel feedstocks is a critical processing step in producing ultralow sulfur transportation fuels. The removal of organonitrogen compounds is necessary to achieve the ultralow sulfur levels since these compounds inhibit sulfur removal. In addition, organosulfur and organonitrogen compounds poison catalysts used in down-stream refinery processes such as hydrocracking, catalytic cracking and reforming. While sulfided Co—Mo/Al2O3 and Ni—Mo/Al2O3 hydrotreatment catalysts are the workhorses of commercial hydrotreating processes, a considerable research effort is ongoing to assess the potential of alternate catalytic materials for hydrotreatment, such as metal phosphides for the hydrodenitrogenation (HDN) and hydrodesulfurization (HDS) reactions. A number of laboratories have investigated the HDS properties of the monometallic phosphides of the first-row transition metals (e.g., Ni2P), of MoP (molybdenum phosphide), and WP (tungsten phosphide) on supports such as silica, as well as the HDS properties of bimetallic phosphide materials. Among the monometallic phosphides, Ni2P has generally been identified as being the most active hydrotreatment catalyst for HDS of thiophene, dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). Some bimetallic phosphide catalysts, Ni2P containing a second first-row metal (e.g., Fe0.03Ni1.97P/SiO2), for example, have exhibited HDS activities that are higher than those of the binary phosphides of the same metals, as well as different product selectivities.
There is a need for Ni2P hydrotreatment catalysts having superior HDS and HDN activities, as well as having improved selectivity for certain hydrotreatment products compared to existing hydrotreatment catalysts. For example, Ni2P hydrotreatment catalysts having higher HDS and HDN activities relative to conventional Co—Mo/Al2O3 and Ni—Mo/Al2O3 sulfide catalysts are desirable. There is also a need for Ni2P hydrotreatment catalysts that can be readily and easily synthesized at low temperatures (T≤400° C.). The present disclosure seeks to fulfill these needs and provides further related advantages.